Controlling device for internal combustion engines



Ju'ne 17, 1941. f E. BECKER 2,245,562

CONTROLLING DEV-ICE FOR INTERNAL coMBUs'I'IoN ENGINES Filed .my so. 1957Patented June 17, 1941 CONTROLLING DEVICE 'FOR INTERNAL CGIVEBUSTIONENGINES Ewald Becker, Berlin-Steglitz, Germany, assignor toAskania-Werke A. G. vormals Centralwerkstatt-Dessau und CarlBamberg-Friedman, a

corporation of Germany Application July 30, 1937, Serial No. 156,571 InGermany August 1, 1936 9 Claims.

This invention relates to improvements in controlling devices, moreparticularly for fuel pumps of internal combustion engines.

Especially in aircraft engines the fuel supply depends on severalfactors of motor operation, on the air density within the induction pipeand on the exhaust counterpressure which naturally varies in dependenceon the altitude at which the aircraft i's flying.

The object of the invention is to provide a simple and reliablecontrolling device by means of which the fuel quantity delivered by thepump is controlled automatically in dependence on the diiierent factorsas functions of engine operation.

A further object of the invention is to facilitate the adjustment of thecontrolling device and to promote reliable operation.

The invention and its aims and objects will be readily understood fromthe following description of an embodiment in which reference is made tothe drawing in which Fig. 1 is a diagrammatic plan view of thecontrolling device;

Fig. 2 is a sectional view of the device.

In the embodiment shown, the controlling device comprises a casing I inwhich is arranged a fluid pressure relay 2, e. g. a sliding valve, aswell as the servo-motor 3. A chamber 5 for a capsule or bellows system 6communicates with the induction pipe of the combustion engine (notshown) through an opening 7. 'I'he capsule system 6 comprises a numberof single capsules or diaphragms 6, 6', 6". Each contains a certainvolume of gas of a predetermined density. If the density of air in thechamber 5, i. e. in the induction pipe of the motor decreases, then thecapsules 6, B', 6", expand, thereby displacing the slide valve 2. bymeans of a pin 8, extending through a wall 4 and a lever 9 linked at 9to the valve 2. By a downward movement of the pin 8 the lever 9 is movedclockwise, resulting in a downward displacement of the valve 2. therebyallowing in a Well known manner the passage of a pressure iiuid, e. g.oil, to the left side of the servo-motor so that its piston I2 will bemoved to the right. To the piston rod I3 is connected an adjustingmember 32 in a manner hereinafter more fully explained, this adjustingmember being adapted in a well known manner to vary the effectivestrokey of the fuel pump I'I, thereby varying the quantity of fuel fedto the motor.

When addusting the effective stroke of the fuel pump by means of themember 32, a restoring action is exerted at the same time on the valve2. The piston rod I3 .is provided with a toothed rack I4 engaging a.pinion I5 fastened to a cam-disc I6, rotatably mounted in .the casing I.One end of the lever 9 rests on said disc as shown in Fig. 2 so thatupon each rotation of the disc corresponding to the movement of thepiston rod, this end of the lever 9 will be displaced upwardly ordownwardly. In the case above mentioned in which the piston rod moves tothe right, the disc will be rotated clockwise so that corresponding tothe curve of the disc, the lever 9 will be swung counter-clockwisearound a pivot-point represented by the pin 8. In this case the valve2is Vpushed upwardly into its middle or neutral position by means of aspring II. Obviously. the valve will be restored by a downward movementin case of a left-hand movement of the servomotor piston I2.

From the foregoing explanation it follows that the stroke of the pistondepends not only on the capsule stroke, but `also on the restoringiniiuence, i. e. on the form given to the cam-disc I6. Therefore, by thechoice of the-curve it is possible to achieve a stroke of the piston I2and the adjusting member 32 which corresponds to the fuel quantityneeded by the motor for any existing air density.

The dependency of the quantity of fuel on the air density isdifferentfor each type of motor, each motor type having a certaincharacteristic with reference to the most favourable fuel consumption.

The entire controlling device may be easily adapted to the special motorcharacteristic by changing the form of the cam I6. For this reason itmay be advisable to arrange the cam I6 in a mannery so'that it may beexchanged. Furthermore, itis possible to arrange several cams side byside so that any cam may be set into operation by an axial displacementof the entire l cam body.

In view of the fact that the form of the lcam is essential for an exactcontrol of the fuel supply in accordance with the motor characteristic,it is desirable to have a long cam surface whichas experience hastaughtmay be manufactured with greater exactness than a short one.v Forthis reason according to the invention the customary restoring camdirectly fastened to the piston rod is replaced by a rotary cam dischaving a long cam path which in spite of its length may be arrangedwithin the smallest space.

With reference to the restoring operation as explalned above theadvantage is to be noted that the distance between the point ofengagement of the cam It and the lever l and its pivot aids il ismaterially greater than the distance between the point of engagement ofthe capsule system 6 and lever 9 from its pivot axis Therefore, the'point of engagement of the cam iii and lever d has a greater stroke thanthe point oi engagement of the capsule system i3 and lever ii, therebyincreasing the exactness of the controlling operation.

f it is desired to control the fuel supply not only in accordance withthe air density in the induction pipe, but also in accordance with theexhaust counter pressure, the temperature of the exhaust gases, thepercentage of carbon-oxide of said gases any other factors or functionsof engine operation, according to the invention, these additionalcontrolling movements may be transmitted to the capsule system 6 in sucha manner that this system is displaced as a Whole inc'iependentlyof theexisting air density. For this purpose the capsule system 5 is notiixedly attached to seid casing l, but is supported by means ofadjusting members adapted to be adjusted by the corresponding additionalcontrolling factor and to displace the capsule system as a whole,thereby transmitting the additional controlling movement to the lever 9and to the adjusting member 32 of the fuel pump in the manner aboveexplained.

As adjusting members for the additional controlling movements, there areprovided in the embodiment shown two screw rings I3 and IS, the outerring i8 being screw threaded into the casing I, while the inner ring I8is screw threaded into 'the outer ring. Into the inner ring I9 by meansof a thread of a diiTer-ent or opposite pitch than the rlrst screwthread is screw threaded a vsupporting member supporting the capsulesystem by means of a thread of a dierent or opposite pitch to the'second screw thread. Each of the screw rings may be independentlyrotated by means of arms itl' and i9', respectively. Furthermore, thesupporting member 2o may likewise be rotated by means of an arm 2li'.Any rotation of the ring i3 or i9 or of the supporting member 2Q resultsin a vertical displacement of the entire capsule system d.

As indicated schematically in Fig. l, the arms it', Iii and 2li areconnected in any convenient manner with the corresponding controldevices El, 25T, 231i, respectively which are responsive to variousfunctions of engine operation. The control device Zi, e. g. may beresponsive to the temperature of the erhaust gases (in the exhaustconduit of the motor) The inner end of the supporting member 2li formswith the upper capsule 5 a chamber 24 which communicates with theatmosphere so that atmospheric pressure exists in this chamber and anychange in said pressure influences the capsule system E. By reason ofthis additional chamber in front of the capsule system 6 being incommunication with the atmosphere there is obtained a correction for thevariation in exhaust back pressure with any change in altitude.

It is to be noted that the controlling device according to the inventionpermits controlling the fuel supply in accordance with a plurality ofindividual factors or functions of engine operation without thenecessity of providing for each factor a special controlling device.

As explained above the chamber communi cates with the induction pipeV ofthe motor through an opening l. The capsule system li in said chamber isprovided to control the servomotor in accordance with the air density inthe induction pipe. As is well known, the air density is a function oithe temperature; therefore, it is important that the air in the chamberE sur rounding the capsule system 6 is caused to have the sametemperature as the air in the induction pipe by permitting a smallamount of air to enter the chamber 5 by any suitable means. For thispurpose, means are further provided to protect the air in the chamber 5against any heating from'outside as e. g. from the heat radiated by themotor cylinders.

In the embodiment shown the casing wall of the chamber 5 is providedwith a heat-insulating layer or lining 25, e. g. a rubber layer having,if desired a good reflecting coating of, i'or example, aluminum bronze.Besides this another heatv1 insulating layer 26 is provided to prevent atransmission of heat from the wall of the c' ring i to the adjustingmembers I8, I 9, 2U of thu capsule system B. Likewise the Wall 4 may beof heat insulating material such as, moulding material having a fabricinsertion so as m act at the same time as a shock absorber or vibrationdampen.

In many cases it may be desired to vary the length of the connecting rodbetween the piston I2 of the servo-motor and the adjusting member 32 ofthe fuel pump I1. Therefore, according to the invention, a turn buckle21 is inserted in said controlling rod, said turn buckle having in awellknown manner a left-hand screw and a righthand screw so that uponrotation of the buckle in one direction the connecting rod is shortenedand upon rotation in opposite direction the connecting rod will belengthened. The buckle El may be rotated automatically during thecontrolling operation of the controlling device to vary the effectivelength of the connecting rod by any controlling device responsive tosome additional function of engine operation which is to be taken intoconsideration,

In case of such an automatic control of the effective length of saidcontrolling rod the turn buckle 21 is provided with teeth 22 in themanner of a gear, said teeth extending axially over the entire length ofthe buckle. (See Fig. 2.) 2! is a worm or spur gear rotatably mounted inthe casing I and meshing with the teeth 28, so that, upon rotation ofthe Worm, the buckle 21 will also be rotated. To the axis of the worm 29is fastened an arm 30 which may be connected in any suitable manner withan additional controlling device, schematically shown at 3l. If thepiston rod I3 is displaced by the piston I2 in the manner described, theteeth 28 of the buckle 2l' slide in the worm 29 without any rotation ofthe buckle 21. On the other hand in spite of a longitudinaldisplacement, the buckle 21 may at any time be rotated by rotation ofthe worm 2S. The device 3| may be adjusted in accordance with the (B. t.u.) heat content o! the fuel per quantity unit, in accordance with thespeed of the engine or of any other factor.

If for any reason the controlling device fails to operate, it isdesirable that the pilot may be able to manually actuate the adjustingmember 552 of the fuel pump I1. As long as the member 32 is rigidlyconnected with the piston I2 of the servo-motor, the manual operationdemands great exertion of strength. For this reason it is advisable toprovide means by which the connec tion between the adjusting member 32and the piston I2 may at any time be broken.

In the embodiment shown this means comprises a yieldable fork 33frictionally ensuing a ball Il iixed to one end of the rod connected tothe piston rod Il by' means of the above mentioned The present inventionis not restricted to the particular embodiment shown and described.

Instead of. a hydraulic relay a pneumatic or electric relay may be usedwithout departing from;

the spirit of the invention as defined in the" aDDended; claims.

What I claim is:

1,'A controlling device for the fuel supplyf means of internalcombustion engines.' comprising a casing divided into -two parts by awally forming an insulated chamber in one part. a4

bellows system provided 'in the insulated part of the casing and forminga pressure responsive device, a pilot 'valve in the other part of thecasing, a piston in the other part of the casing controlled by saidpilot valve. a rod connected to the piston and extending through thecasing to the fuel supply means. means extending from the insulated partof the casing for transferring themovementof the bellows system to thepilot valve, and a cam in the other part of the casing operativelyconnected to the transfer means to return the pilot valve by thetransfer means to its initial position after a displacement of thepiston due to a movement of the bellows system.

2. A controlling device according to claim l. in which' an independentlyadjustable device is provided in thol'rod. and means 'are provided tooperate the adjustable device in dependence upon a function of theengine operation such as the temperature of the exhaust gases, the backpressure of the exhaust gases and the composition of the exhaust gases.x

3. A controlling device according to claim 1. in which means areprovided in the form of a supporting member in the insulated chamber formpending the bellows System in said insulating chamber. d in which meansare provided in the casing to adjust the position of the support- 'ingmemberrelative to the transfer means.

4. A controlling device for the fuel supply means of internal combustionengines, comprising an element for adiusting.the fuel amount deliveredto said engine, a servo-motor operatively connected to said element, avalve connected to control said servo-motor, and a pressure responsivesystem connected to act upon said valve, said system including a bellowsresponsive' to air intake pressure and temperature, and means forming achamber connected to the atmosphere. said bellows being arranged sothatthe end thereof opposite to the valve connection constitutes aflexible end wall of said chamber. 5. A device according to claim 4, inwhich said chamber is provided with a rigid wail serving as a mountingfor the bellows.

6. A device as claimed in claim 4, in which means are provided fordisplacing said bellows and said chamber as a whole in response to anyadditional function of engine operation such as the temperature of theexhaust gases, the back pressure of the exhaust gases and thecomposition of the exhaust gases.

7. A device as claimed in claim 4, including a tube which is connectedto the outer wall of said additional chamber and an external housingenclosing said bellows and said chamber, said tube being axiallyadjustable in said housing.

8. A device as claimed in-claim.4, including a screw-threaded tubeconnected to the outer wall of said chamber and an external housingenclosing said bellows and said chamber, said tube being screw threadedinto said housing for adjustment thereof.

9. A device as claimed in claim 4, including a carrier for the pressureresponsive system, an external housing forI enclosing said system andseparately adjustable control members responsive to further functions ofengine operation and disposed between the carrier and said externalhousing, said control members arranged to support the carrier.

EWALD BECKER.

